Determining the role of PA2449 in pyocyanin biosynthesis in Pseudomonas aeruginosa, PAO1

Pseudomonas aeruginosa PAO1 is an opportunistic pathogen known to have an arsenal of virulence factors that can affect immunocompromised patients. One of these virulence factors is the redox-active phenazine compound, pyocyanin. The production of pyocyanin is regulated by multiple mechanisms, which include stress response and quorum sensing (QS). In a previous study, we found that the PA2449 gene was required for the biosynthesis of QS homoserine lactones and pyocyanin. This study focused on a particular strain of P. aeruginosa that lacked the ability to produce pyocyanin. We restored the production of pyocyanin in this strain by inserting a vector encoding a gene responsible for pyocyanin biosynthesis, rhlI. We then did various studies to determine the levels at which the toxin was produced compared to the wild type strain. We found that in smaller volumes of medium, the mutant strain production levels were similar to the wild type, 219 μM. In larger volumes of media the two strains produced a similar amount of pyocyanin although the timing of the production between the two strains was different, 4.5 hours for the wild type and 9 hours for the mutant strain containing the vector. We also analyzed other strains with knockouts relevant to the PA2449 gene. This led us to discover the potential role for PA2449 in pyocyanin production, in repressing the expression of MexEF- OprN allowing the intracellular accumulation of PQS. This study will allow us to further understand the mechanisms that Pseudomonas, as well as other bacteria, use when producing toxins

The effect of focus correction on the writing of urban seventh grade students using the cumulative writing folder program across the curriculum.

The purpose of this study was to determine if the focus correction strategy of the Cumulative Writing Folder Program had a positive effect on students\u27 overall writing skills and on the major writing areas of mechanics, style, content and organization. A pre and post exploratory study was used in this research with a sample of 22 grade 7 urban middle school students. The study looked for significant differences between high and low repetitions of focus correction areas (FCAs) and their effect on achievement. Writing samples were assessed with holistic and primary trait scoring. The important findings of this study are that: (1) The Cumulative Writing Folder Program works and produces significant increases in students\u27 writing skills overall and for all variables studied: mechanics, style, content and organization (p $\u3c$.001). It especially works as a way to focus teachers\u27 attention on writing and as a means for teachers and administrators to provide a set of strategies that everyone can use. (2) A balance of FCAs should be used. An overemphasis on mechanics may actually decrease students\u27 mechanical skills. (3) The frequency of FCAs may not be as important as the focusing of the correction itself. These results are all the more meaningful because they were achieved in an inner city middle school with minority students. They reinforce the notions that an atmosphere of literacy can be created, good writing can be taught, and classroom practices make a difference. Further research must be done to determine if the positive results were due to frequency of writing, consistency of approach, the management system, oral reading, or using past papers to teach new skills which are the other major components of this program, or to the atmosphere of literacy at the study school, and to find out what number of Focus Correction Area repetitions works best. Additionally a study should be done to examine which individual focus correction areas have the greatest effect on writing performance. When research responds to these issues, American schools will produce more effective writers and the teaching of writing will be close to reaching its potential

Chemical and isotopic signature of groundwater in the Santa Ninfa karst system and possible inferences on neotectonics

The Santa Ninfa karst system is an area strongly controlled by tectonics, whose intense fracturing gave rise to the formation of a large number of cavities that foster the drainage of water. The hydrogeochemical characters of groundwater circulating in this aquifer, together with its isotopic signature, were investigated in detail. The chemistry of groundwater reflects the nature of the rocks hosting the aquifers, constituted by primary and diagenetic selenitic gypsum, salts, and gypsum- arenite, whose dissolution is responsible of the geochemical fingerprint of the quasi-totality of the samples. A single site (CAM) is characterised by a different chemical composition, indicating a mixing between Ca-sulphate, Ca-bicarbonate and a NaCl-rich water. From the chemical point of view, no evidence of interaction between shallow groundwater and deep fluids has been detected. Conversely, isotopic fluctuations highlight mixing processes between surficial (evaporated) runoff and groundwater. Different mixing proportion among these endmembers can be reflected in variations of the chemical character of the sampled springs. Changes in mixing proportions can be the effect of differential permeability variations, in turn produced by local stress field changes during seismogenic processes. In this scenario the geochemical monitoring of the Santa Ninfa karst aquifer could be of relevant interest in the study of seismogenic processes in this area, with particular reference to the relationship between seismic and geochemical transients

Fluids Geochemistry of Stromboli

An accurate description of the geochemical system is presented here based on a review of scientific work performed during the past decade. The surface manifestations of the volcanic system of Stromboli have been investigated using several measuring techniques. Studying the chemical composition of the volcanic plume and of fumarolic emissions has provided information on magma degassing processes. The total fluxes of the emitted gases from both the plume and the soil were found to vary with changes in volcanic activity (from normal Strombolian activity to effusive and/or paroxysmal activity). Thermal water results from the interaction between volcanic gases, host rock, seawater and meteoric water and temporal changes observed in the chemical and the isotopic composition of the gases dissolved into thermal waters highlighted the rising of new magma batches. Combining modelling of gas-water-rock interactions with an understanding of the volcanic system allowed to identify preferential sampling sites and parameters for the geochemical monitoring of volcanic activity at Stromboli Island

Geomorphological and geochemical characterization of the 11 August 2008 mud volcano eruption at S. Barbara village (Sicily, Italy) and its possible relationship with seismic activity

On 11 August 2008 a paroxysmal eruption occurred at Santa Barbara mud volcano (MV), located close to Caltanissetta, one of the most densely populated cities of Sicily (Italy). An associated minor event took place on August 2009. Both the events caused severe damage to civil infrastructures located within a range of about 2 km from the eruptive vent. Geomorphological, geochemical, and seismological investigations were carried out for framing the events in the appropriate geodynamic context. Geomorphological surveys recognized, in the immediate surrounding of the main emission point, two different families of processes and landforms: (i) ground deformations and (ii) changes in morphology and number of the fluid emitting vents. These processes were associated to a wider network of fractures, seemingly generated by the shock wave produced by the gas blast that occurred at the main paroxysm. Geochemical characterization allowed an estimation of the source of the fluids, or at least their last standing, at about 3 km depth. Finally, the close time relationships observed between anomalous increments of seismic activity and the two main paroxysmal events accounted for a possible common trigger for both the phenomena, even with different timing due to the very different initial conditions and characteristics of the two processes, i.e. seismogenesis and gas overloading